However, when given the choice, as you noted, the optimized version is almost always preferable, particularly when one sees them side-by-side.

That's not exactly what I said and not what I meant. Rather the opposite. While I'm not going to complain about getting more detail, I'm yet to see an image of mine where the extra detail from one converter compared to another would make any practical difference. The technical areas where I do see a practical difference are in the handling of colour and high-ISO noise under artificial light. and I don't think the so-called niche converters do well in these areas. But none of these make a good image bad or a bad image good. Which is why this emphasis on detail troubles me.